This meter tracks the Twitter Political Index, a daily measure of sentiment expressed by Twitter users about President Obama and Mitt Romney. The index, similar to a favorability rating, is calculated on a scale of 0 to 100, with 100 being the most positive. Sample tweets are culled from those frequently mentioned that day. Full Story.

These meters track a subset of the Twitter Political Index, measuring Twitter sentiment toward President Obama and Mitt Romney through a sample of tweets from 12 key battleground states: Colorado, Florida, Iowa, Michigan, Nevada, New Hampshire, New Mexico, North Carolina, Ohio, Pennsylvania, Virginia and Wisconsin. The data for the states is aggregated and not available for the individual states. Because it is a smaller sample, the results are more volatile than the national meter. Topsy Labs provides this data to USA TODAY every two weeks.

Twitter sentiment for:

About the project

The USA TODAY/ Twitter Election meter is a graphic representation of the Twitter Political Index, a daily number produced by Twitter in partnership with Topsy Labs and polling firms The Mellman Group and North Star Opinion Research. The index is not intended to replace traditional polling, but to provide a daily snapshot of the sentiment of political conversation on Twitter. Unlike traditional polling, in which participants are scientifically selected, contacted and asked a series of questions, the Twitter Political Index is based on gathering the volunteered opinions of people logging on to Twitter. The result is analogous to describing the general tone of political discussion overheard in a café on a given day.

Because the discussion of topics on Twitter fluctuates wildly, the daily index number is a weighted calculation based on three days worth of tweets, with most weight given to the most recent day’s tweets. The index is based on analysis of nearly 2 million tweets each week that mention Romney or Obama.

Sample tweets are provided by Topsy.

Read USA TODAY's story about the Twitter Political Index and social media sentiment analysis here.